The redshifts of quasars

It has been shown that no correlation exists between the inferred ejection velocities of quasar absorption lines and the intrinsic continuum flux. In the absence of a net force on the absorbing clouds this disproves intrinsic models which rely on radiative acceleration for the production of these lines.It has also been shown that there is a statistically significant excess of quasar alignments over that expected at a specific deviation (four arc - seconds) of the central object from the line defined by the outlying members. The narrowness of this peak makes it difficult to explain as the product of simple quasar clustering.Observation at high spectral resolution om two quasars lying in such alignments has shown no significant deviations of the absorption line distribution from the norm. Assuming that this is true for all such objects and that a significant proportion of the quasar redshift is gravitational then the observed upper limits on the rate of change of absorption line redshifts has enabled lower bounds to be placed upon the central mass. The derived masses are very large and apparently in conflict with galactic stability arguments.Number / magnitude distributions have been determined for two samples of quasar candidates which were previously uncalibrated

Mass transport in galaxy discs limits black hole growth to sub-Eddington rates

Super-massive black holes (SMBHs) observed to have masses of $M_\bullet \sim 10^9 \, \mathrm{M_\odot}$ at $z\gtrsim6$, $<1$ Gyr after the Big Bang, are thought to have been seeded by massive black holes which formed before growing concurrently with the formation of their host galaxies. We model analytically the idealised growth of seed black holes, fed through gas inflow from growing proto-galaxy discs. The inflow depends on the disc gravitational stability and thus varies with black hole and disc mass. We find that for a typical host halo, the efficiency of angular momentum transport, as parametrised by the disc viscosity, is the limiting factor in determining the inflow rate and the black hole accretion rate. For our fiducial case we find an upper black hole mass estimate of $M_\bullet \sim 1.8 \times 10^7 \, \mathrm{M_{\odot}}$ at $z=6$. Only in the extreme case of $\sim 10^{16}$ M$_{\odot}$ haloes at $z=6$ produces SMBH masses of $\sim 10^9$ M$_{\odot}$. However, the number density of such haloes is many orders of magnitude below the estimated 1 Gpc$^{-3}$ of SMBHs at $z=6$, indicating that viscosity driven accretion is too inefficient to feed the growth of seeds into $M_\bullet \sim 10^9 \, \mathrm{M_\odot}$ SMBHs by $z \sim 6$. We demonstrate that major mergers are capable of resolving the apparent discrepancy in black hole mass at $z=6$, with some dependence on the exact choice of orbital parameters of the merger.Comment: 13 pages, 9 figures, accepted for publicatio

The prospect of artificial intelligence to personalize assisted reproductive technology

The Department of Metabolism, Digestion, and Reproduction is funded by grants from the MRC and NIHR. S.H. is supported by the UKRI CDT in AI for Healthcare http://ai4health.io (EP/S023283/1). A.A. is supported by an NIHR Clinician Scientist Award (CS-2018-18-ST2-002). M.V. and K.T.A. are supported by the EPSRC (EP/T017856/1). W.S.D. is supported by an NIHR Senior Investigator Award (NIHR202371).Infertility affects 1-in-6 couples, with repeated intensive cycles of assisted reproductive technology (ART) required by many to achieve a desired live birth. In ART, typically, clinicians and laboratory staff consider patient characteristics, previous treatment responses, and ongoing monitoring to determine treatment decisions. However, the reproducibility, weighting, and interpretation of these characteristics are contentious, and highly operator-dependent, resulting in considerable reliance on clinical experience. Artificial intelligence (AI) is ideally suited to handle, process, and analyze large, dynamic, temporal datasets with multiple intermediary outcomes that are generated during an ART cycle. Here, we review how AI has demonstrated potential for optimization and personalization of key steps in a reproducible manner, including: drug selection and dosing, cycle monitoring, induction of oocyte maturation, and selection of the most competent gametes and embryos, to improve the overall efficacy and safety of ART.Peer reviewe

Optimization of a parallel permutation testing function for the SPRINT R package

The statistical language R and its Bioconductor package are favoured by many biostatisticians for processing microarray data. The amount of data produced by some analyses has reached the limits of many common bioinformatics computing infrastructures. High Performance Computing systems offer a solution to this issue. The Simple Parallel R Interface (SPRINT) is a package that provides biostatisticians with easy access to High Performance Computing systems and allows the addition of parallelized functions to R. Previous work has established that the SPRINT implementation of an R permutation testing function has close to optimal scaling on up to 512 processors on a supercomputer. Access to supercomputers, however, is not always possible, and so the work presented here compares the performance of the SPRINT implementation on a supercomputer with benchmarks on a range of platforms including cloud resources and a common desktop machine with multiprocessing capabilities

FireGrid: Integrated emergency response and fire safety engineering for the future built environment

FireGrid is researching the development and integration of modelling, sensors, Grid, HPC, and C/C technologies. It will stimulate further research, in new safety systems and strategies, in new sensor technologies, in improved modelling techniques and in Grid technologies and operation. By integrating previously uncoupled tools, FireGrid will allow true performance-based design for the built environment. It will introduce a new emergency response paradigm, using scenarios planned and stored in advance in conjunction with super-real-time simulation. Deployment of FireGrid will reduce costs and save lives